People often send other users documents and images. These files are often of different formats or fonts, as a user could send a Microsoft Word file (.doc file) or a GNU image manipulation program (GIMP) image (.xcf) via email, instant messaging or even on physical media.
Applications can view many different fonts and font scripts in the same document. For example, a document can be created that has right-to-left formatted Arabic script in one section and left-to-right Latin script in another. Due to the nature of how fonts are created and packaged, not all fonts contain all glyphs. In addition, often font designers only do the minimum of characters, such as a-z, A-Z and 1-9. Accented characters such as ‘ã’ may not be included in the font set, and it is even less likely that characters such as ‘’ will be included. Only a few fonts are installed by default on most operating system (OS) distributions as the fonts are relatively large in size.
Typically in an application, the missing glyphs are shown as black squares with hexadecimal numbers so that a user is aware that some characters are not displayable or recognizable. One solution is for the user to download and install additional fonts that have the required glyphs, usually a specialist font for that language. However, the user has to know what font to download, and it may take the user a few attempts in order to get the right one. As a result, the user has to stop what he/she is doing, and manually search for and install the proper font packages.